Surfactant selection for downhole treatments

Abstract

Evaluating surfactants for use in downhole applications, especially surfactants with similar surface tension or interfacial tension values and wetting properties, may be achieved with a sensitive column test using a non-uniform particulate media therein. An exemplary method may include providing a column containing two types of particles that differ by at least one of: a mean particle diameter, a sphericity, and a chemical composition. Surfactant samples may be individually tested by passing the sample through the column followed by a displacement fluid, typically an oleaginous. The displacement rate and volume of the surfactant sample may be used to assess the surfactant's suitability for downhole applications.

The invention claimed is: 
     
       1. A method comprising:
 providing a column containing first particles and second particles, wherein the first particles differ from the second particles by at least one property selected from the group consisting of: a mean particle diameter, a sphericity, and a chemical composition; 
 providing a plurality of surfactant samples that are different and each comprise a base fluid and at least one surfactant; 
 measuring a displacement rate and a displacement volume for the plurality of surfactant samples according to the following procedure:
 flowing the surfactant sample and then an oleaginous fluid through at least a portion of the column; 
 measuring the displacement rate at which the oleaginous fluid displaces the surfactant sample; and 
 measuring the displacement volume for which the oleaginous fluid displaces the surfactant sample; 
 
 comparing the displacement rate and the displacement volume of each of the plurality of surfactant samples; and 
 ranking the plurality of surfactant samples based on the displacement rate and the displacement volume, thereby producing a sample ranking. 
 
     
     
       2. The method of  claim 1 , wherein the first particles differ from the second particles by the mean particle diameter, and wherein the mean particle diameter of the first and second particles are each between about 38 microns and about 8 millimeters. 
     
     
       3. The method of  claim 1 , wherein the first particles differ from the second particles by the sphericity, and wherein the sphericity of the first and second particles are each between about 0.2 to about 1.0. 
     
     
       4. The method of  claim 1 , wherein the first particles provide for a column mean pore size of about 1 micron to about 200 microns. 
     
     
       5. The method of  claim 1 , wherein the second particles provide for a column mean pore size of about 1 micron to about 200 microns. 
     
     
       6. The method of  claim 1 , wherein the first and the second particles each provide for a column mean pore size of about 1 micron to about 200 microns such that the column mean pore size provided by the first particles is less than the column mean pore size provided by the second particles. 
     
     
       7. The method of  claim 6 , wherein the first particles are proximal to a fluid exit port of the column as compared to a location of the second particles in the column. 
     
     
       8. The method of  claim 1 , wherein the first particles differ from the second particles by the mean particle diameter, the sphericity, and the chemical composition. 
     
     
       9. The method of  claim 1 , wherein flowing the surfactant sample and then the oleaginous fluid through at least a portion of the column includes applying a pressure to the oleaginous fluid. 
     
     
       10. The method of  claim 9 , wherein the pressure is a constant pressure. 
     
     
       11. The method of  claim 1  further comprising: formulating a treatment fluid additive for a flow back operation in a subterranean formation based on the sample ranking. 
     
     
       12. A method comprising:
 providing a column containing first particles and second particles, wherein the first particles differ from the second particles by at least one property selected from the group consisting of: a mean particle diameter, a sphericity, and a chemical composition; 
 providing a plurality of surfactant samples that are different and each comprise a base fluid and at least one surfactant; 
 measuring a change in a variable pressure applied to an oleaginous fluid for the plurality of surfactant samples according to the following procedure:
 flowing the surfactant sample and then an oleaginous fluid through at least a portion of the column; 
 applying a variable pressure to the oleaginous fluid to provide for a constant displacement rate; 
 measuring the change in the variable pressure; 
 
 comparing the change in the variable pressure of each of the plurality of surfactant samples; and 
 ranking the plurality of surfactant samples based on the change in the variable pressure, thereby producing a sample ranking. 
 
     
     
       13. The method of  claim 12 , wherein the first particles differ from the second particles by the mean particle diameter, and wherein the mean particle diameter of the first and second particles are each between about 38 microns and about 8 millimeters. 
     
     
       14. The method of  claim 12 , wherein the first particles differ from the second particles by the sphericity, and wherein the sphericity of the first and second particles are each between about 0.2 to about 1.0. 
     
     
       15. The method of  claim 12 , wherein the first particles provide for a column mean pore size of about  1  micron to about 200 microns. 
     
     
       16. The method of  claim 12 , wherein the second particles provide for a column mean pore size of about 1 micron to about 200 microns. 
     
     
       17. The method of  claim 12 , wherein the first and the second particles each have a mean pore size of about 1 micron to about 200 microns such that the column mean pore size provided by the first particles is less than the column mean pore size provided by the second particles. 
     
     
       18. The method of  claim 17 , wherein the first particles are proximal to a fluid exit port of the column as compared to a location of the second particles in the column. 
     
     
       19. The method of  claim 12  further comprising: formulating a treatment fluid additive for a flow back operation in a subterranean formation based on the sample ranking. 
     
     
       20. A system comprising:
 a wellhead with a tubular extending therefrom and into a wellbore in a subterranean formation; and 
 a pump fluidly coupled to a tubular, the tubular containing a treatment fluid that comprises the treatment fluid additive of  claim 19 .